

#if defined(ORTP_SUPPORT) || defined(CRIS_SUPPORT) || defined(UCL_SUPPORT)

/*
 *  PCM - A-Law conversion
 *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
 *
 *  Wrapper for linphone Codec class by Simon Morlat <simon.morlat@free.fr>
 */

int
val_seg (int val)
{
  int r = 0;

  val >>= 7;
  if (val & 0xf0)
    {
      val >>= 4;
      r += 4;
    }
  if (val & 0x0c)
    {
      val >>= 2;
      r += 2;
    }
  if (val & 0x02)
    r += 1;
  return r;
}

/*
 * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law
 *
 * s16_to_alaw() accepts an 16-bit integer and encodes it as A-law data.
 *
 *		Linear Input Code	Compressed Code
 *	------------------------	---------------
 *	0000000wxyza			000wxyz
 *	0000001wxyza			001wxyz
 *	000001wxyzab			010wxyz
 *	00001wxyzabc			011wxyz
 *	0001wxyzabcd			100wxyz
 *	001wxyzabcde			101wxyz
 *	01wxyzabcdef			110wxyz
 *	1wxyzabcdefg			111wxyz
 *
 * For further information see John C. Bellamy's Digital Telephony, 1982,
 * John Wiley & Sons, pps 98-111 and 472-476.
 */

unsigned char
s16_to_alaw (int pcm_val)
{
  int mask;
  int seg;
  unsigned char aval;

  if (pcm_val >= 0)
    {
      mask = 0xD5;
  } else
    {
      mask = 0x55;
      pcm_val = -pcm_val;
      if (pcm_val > 0x7fff)
        pcm_val = 0x7fff;
    }

  if (pcm_val < 256)
    aval = pcm_val >> 4;
  else
    {
      /* Convert the scaled magnitude to segment number. */
      seg = val_seg (pcm_val);
      aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f);
    }
  return aval ^ mask;
}

/*
 * alaw_to_s16() - Convert an A-law value to 16-bit linear PCM
 *
 */
int
alaw_to_s16 (unsigned char a_val)
{
  int t;
  int seg;

  a_val ^= 0x55;
  t = a_val & 0x7f;
  if (t < 16)
    t = (t << 4) + 8;
  else
    {
      seg = (t >> 4) & 0x07;
      t = ((t & 0x0f) << 4) + 0x108;
      t <<= seg - 1;
    }
  return ((a_val & 0x80) ? t : -t);
}

/*
 * s16_to_ulaw() - Convert a linear PCM value to u-law
 *
 * In order to simplify the encoding process, the original linear magnitude
 * is biased by adding 33 which shifts the encoding range from (0 - 8158) to
 * (33 - 8191). The result can be seen in the following encoding table:
 *
 *	Biased Linear Input Code	Compressed Code
 *	------------------------	---------------
 *	00000001wxyza			000wxyz
 *	0000001wxyzab			001wxyz
 *	000001wxyzabc			010wxyz
 *	00001wxyzabcd			011wxyz
 *	0001wxyzabcde			100wxyz
 *	001wxyzabcdef			101wxyz
 *	01wxyzabcdefg			110wxyz
 *	1wxyzabcdefgh			111wxyz
 *
 * Each biased linear code has a leading 1 which identifies the segment
 * number. The value of the segment number is equal to 7 minus the number
 * of leading 0's. The quantization interval is directly available as the
 * four bits wxyz.  * The trailing bits (a - h) are ignored.
 *
 * Ordinarily the complement of the resulting code word is used for
 * transmission, and so the code word is complemented before it is returned.
 *
 * For further information see John C. Bellamy's Digital Telephony, 1982,
 * John Wiley & Sons, pps 98-111 and 472-476.
 */

unsigned char
s16_to_ulaw (int pcm_val)       /* 2's complement (16-bit range) */
{
  int mask;
  int seg;
  unsigned char uval;

  if (pcm_val < 0)
    {
      pcm_val = 0x84 - pcm_val;
      mask = 0x7f;
  } else
    {
      pcm_val += 0x84;
      mask = 0xff;
    }
  if (pcm_val > 0x7fff)
    pcm_val = 0x7fff;

  /* Convert the scaled magnitude to segment number. */
  seg = val_seg (pcm_val);

  /*
   * Combine the sign, segment, quantization bits;
   * and complement the code word.
   */
  uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f);
  return uval ^ mask;
}

/*
 * ulaw_to_s16() - Convert a u-law value to 16-bit linear PCM
 *
 * First, a biased linear code is derived from the code word. An unbiased
 * output can then be obtained by subtracting 33 from the biased code.
 *
 * Note that this function expects to be passed the complement of the
 * original code word. This is in keeping with ISDN conventions.
 */
int
ulaw_to_s16 (unsigned char u_val)
{
  int t;

  /* Complement to obtain normal u-law value. */
  u_val = ~u_val;

  /*
   * Extract and bias the quantization bits. Then
   * shift up by the segment number and subtract out the bias.
   */
  t = ((u_val & 0x0f) << 3) + 0x84;
  t <<= (u_val & 0x70) >> 4;

  return ((u_val & 0x80) ? (0x84 - t) : (t - 0x84));
}




void
mulaw_dec (char *mulaw_data /* contains size char */ ,
           char *s16_data /* contains size*2 char */ ,
           int size)
{
  int i;

  for (i = 0; i < size; i++)
    {
      *((signed short *) s16_data) = ulaw_to_s16 ((unsigned char) mulaw_data[i]);
      s16_data += 2;
    }
}

void
mulaw_enc (char *s16_data /* contains pcm_size char */ ,
           char *mulaw_data /* contains pcm_size/2 char */ ,
           int pcm_size)
{
  int i;
  int limit = pcm_size / 2;

  for (i = 0; i < limit; i++)
    {
      mulaw_data[i] = s16_to_ulaw (*((signed short *) s16_data));
      s16_data += 2;
    }
}

void
alaw_dec (char *alaw_data /* contains size char */ ,
          char *s16_data /* contains size*2 char */ ,
          int size)
{
  int i;

  for (i = 0; i < size; i++)
    {
      ((signed short *) s16_data)[i] = alaw_to_s16 ((unsigned char) alaw_data[i]);
    }
}

void
alaw_enc (char *s16_data /* contains 320 char */ ,
          char *alaw_data /* contains 160 char */ ,
          int pcm_size)
{
  int i;
  int limit = pcm_size / 2;

  for (i = 0; i < limit; i++)
    {
      alaw_data[i] = s16_to_alaw (*((signed short *) s16_data));
      s16_data += 2;
    }
}

#endif
